1. Field of the Invention
The present invention relates to an image processing apparatus that selects, synthesizes, and outputs image signals received by a plurality of receiving units, and relates to a control method therefor.
2. Description of the Related Art
Broadcast digitalization has enabled multi-channel broadcasting. The way of watching a multi-channel broadcast including arranging a plurality of windows on a single display screen and assigning images on different channels to their corresponding windows is becoming popular. For example, as shown in FIG. 16A, two display areas are arranged on the display screen 201 of a television, one of which is assigned as a main-window 202 and the other as a sub-window 203, and two images are displayed in the corresponding windows. Soccer telecast program and baseball telecast program are displayed in the main-window 202 and sub-window 203 respectively, making it possible to check the baseball game any time while watching the soccer game. Actually, a television capable of displaying a plurality of windows on a display screen has achieved the practical use.
Conventionally, where a power source is turned off when a television is watched in a multi-window, and turned on thereafter, an image displayed in the main-window 202 previously is again displayed on the entire display screen 201 (see, FIG. 16B).
A technique has been proposed in which pieces of information corresponding to a plurality of windows displayed on a display screen are stored and images are displayed in many windows based on these pieces of information. In Japanese Patent Application Laid-Open (JP-A) No. 11-136595, a main-window is displayed over the display screen of a television and a plurality of sub-windows is arranged on parts of the main-window. The device disclosed in JP-A No. 11-136595 has a means for displaying images in the main-window and sub-windows and a means for storing the position and size of each window and identification information for each program, thereby enabling reproduction in the plurality of windows on the display screen, based on each of the pieces of the stored information.